Examination of feline leukemia virus (FeLV) and murine leukemia virus (MuLV) to investigate the regulation of infection, production and assembly of oncornavirus and virus-associated cell surface antigen (CSA). This includes: a) study of the kinetics of biosynthesis of FeLV and FeLV CSA; b) assessment of the effect of streptonigrin on several aspects of FeLV infection and production; c) characterization of CSA with respect to virion components; d) characterization of the degree of cross-reaction of FeLV-CSA and MuLV-CSA; and e) characterization of the regulation expression of FeLV and CSA in cat x mouse cell hybrids. Examination of the character, extent and regulation of cellular structural gene dysfunction in transformed cells. The analysis includes: a) examination of 20 randomly selected isoenzyme gene products for gene dysfunction in transformed tissue culture lines; b) examination of 25 major soluble proteins in the same lines; c) examination of surface components of the same lines. The analysis is being performed on chemically and virally transformed cell lines; and d) genetic analysis of the regulation of aberrant gene products and their relationship or synteny to the transformed phenotype. Genetic analysis of tumorigenicity in culture, including: a) segregation analysis of tumorigenicity and chromosomal segregation in somatic cell hybrids; b) genetic complementation matrix of tumorigenicity in a number of independently transformed lines.